Adjustments
HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual 7-19
455 kHz IF and noise limiter alignment
108-04962 and 08-05322
There are two tuned transformers in the 455 kHz IF circuit located on the
Rx/Exciter PCB. T201 is located in the IF path to the sideband filter. T202 is
located at the output of the noise limiter 455 kHz amplifier.
The alignment may be carried out either in the Test mode or normal operating
mode.
Aligning the transformers in the 455 kHz IF circuit on the Rx/Exciter PCB
q Select any receive channel.
q Connect a signal generator to the receiver input. It should be set to 1 kHz
above the selected channel frequency (1 kHz below for LSB) at an output of
about 10 mV EMF.
q Fit a shorting link to B–E to disable the noise limiter gate.
q Connect an oscilloscope using a 10X probe to TP201. Set the oscilloscope
as follows:
Timebase
50 µs per division
Channel One
50 mV per division (equals 0.5 V per
division with the attenuation of the 10X
probe)
Trigger
Auto
q Adjust T201 for maximum amplitude.
Only a small change in amplitude will be seen due to the low Q of the tuned
circuit.
q Remove the 10X probe from TP201.
q Connect a 1X probe to position A (part of noise limiter TP202).
q Set the oscilloscope to a sensitivity of 10 mV per division.
q Adjust T202 for maximum amplitude.
q Remove the shorting link to B–E and return it to its parking position (link
E–E).
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